Different kinds of vehicle control arrangements configured to control velocity and/or steering of a vehicle have been developed. They can be divided into different categories based on the level of control of the vehicle hosting the control arrangement. In the United States, the National Highway Traffic Safety Administration (NHTSA) has proposed the following formal classification system:
Level 0: The driver completely controls the vehicle at all times.
Level 1: Individual vehicle controls are automated, such as electronic stability control or automatic braking.
Level 2: At least two controls can be automated in unison, such as adaptive cruise control in combination with lane keeping.
Level 3: The driver can fully cede control of all safety-critical functions in certain conditions. The vehicle senses when conditions require the driver to retake control and provides a “sufficiently comfortable transition time” for the driver to do so.
Level 4: The vehicle performs all safety-critical functions for the entire trip, with the driver not expected to control the vehicle at any time. As this vehicle would control all functions from start to stop, including all parking functions, it could include unoccupied cars.
An adaptive cruise control is a cruise control system for road vehicles that controls vehicle velocity and automatically adjusts the vehicle velocity to maintain a safe distance to preceding vehicles. A lane keeping system is a system controlling steering of a road vehicle to ensure the road vehicle stays in its lane. A vehicle comprising adaptive cruise control and a lane keeping system thus falls in the Level 2 category above. Vehicles falling in the categories Level 3 and Level 4 are under development.
All vehicles falling into categories 2-4 must be equipped some kind of remote sensors arranged to acquire vehicle surrounding information to allow control of steering and/or velocity on the basis of the acquired vehicle surrounding information. Such acquiring of vehicle surrounding information can be performed with good reliability in most situations by means of remote sensors such as RADAR (RAdio Detection And Ranging) sensors and/or LASER (Light Amplification by Stimulated Emission of Radiation) sensors, and/or LIDAR (LIght Detection And Ranging) sensors, and/or imaging sensors. Even though such acquiring of vehicle surrounding information can be performed with good reliability in most situations, it is a complex task to always acquire vehicle surrounding information in a correct manner due to the variation of road types, lane markings, weather conditions etc. If an error occurs in the control of steering of the road vehicle, whether based on erroneously acquired vehicle surrounding information or not, it may have severe consequences.
Therefore, there is room for an improved vehicle control arrangement providing an improved safety of travel of a road vehicle.